Fludarabine phosphate is a fluorinated nucleotide analog of the antiviral drug vidarabine that is relatively resistant to the deamination of adenosine deaminase and is generally used in the treatment of chronic lymphocytic leukemia, it can be rapidly dephosphorylated to 2F-ara-A in human body, and 2F-ara-A can be taken up by cells and then it becomes an active triphosphate 2F-ara-ATP after being phosphorylated by intracellular deoxycytidine kinase. The metabolite can inhibit the synthesis of DNA by inhibiting nucleotide reductase, DNA polymerase α, δ and ε, DNA primase and DNA ligase. In addition, RNA polymerase II can also be partially inhibited to reduce the synthesis of protein.
The chemical name of fludarabine phosphate is: 9-β-D-arabinofuranosyl-2-fluoroadenine-5′-phosphate, the structural formula is as follows:

For polymorphic drugs, different crystal forms can have different physical and chemical properties, including melting point, chemical stability, apparent solubility, dissolution rate, optical and mechanical properties etc. These physicochemical properties directly determine whether a specific crystal form can prepare pharmaceutical preparations, and affect the quality of APIs and preparations. Therefore, for pharmaceutical formulations, it is essential to develop new crystal forms with excellent solubility and dissolution rates to meet the demanding requirements of pharmaceuticals.